What is the uterus?

• A. Internal organs in the main cavities (singular: viscus)
• B. Groups of organs working together to perform particular complex functions (jobs in the body)
• C. The womb; the organ that holds the embryo/fetus as it develops. Only in women
• D. The reproductive system organs

Answer: (C)

The uterus is the womb—the muscular organ in the female reproductive system where a fertilized egg implants and grows into a fetus. It’s a pear-shaped structure in the pelvis, with a thick muscular wall (the myometrium) and a lining (the endometrium) that thickens each cycle in preparation for pregnancy. If pregnancy occurs, the embryo embeds into that lining and develops there, nourished by the placenta. During labor, the uterine muscles contract to help push the baby out. This description directly names the uterus as the organ that holds and develops the embryo/fetus, which is why it’s the best answer. The other options describe broader ideas (general internal organs, groups of organs assigned to functions, or the entire reproductive system) rather than identifying this specific organ.